.MH "Filling and Margin Adjustment"
.#
.SH "Filled Text"
'Fmt' collects as many words as will fit on a single output line
before actually writing it out, regardless of line boundaries in its
input stream. This is called 'filling' and is standard practice for
'fmt'.
It can, however, be turned off with the 'no-fill' command
.be
 [bf .nf]
.ee
and lines thenceforth will be copied from input to output unaltered.
When you want to turn filling back on again,
you may do so with the 'fill' command
.be
 [bf .fi]
.ee
and 'fmt' will resume its normal behavior.
.pp
If there is a partially filled line that has not yet been
written out when an [bf nf]
command is encountered, the line is forced out before any other
action is taken.
This phenomenon of forcing out a partially filled line is known as a
'break' and occurs implicitly with many formatting commands. To
cause one explicitly, the 'break' command
.be
 [bf .br]
.ee
is available.
.#
.SH "Hyphenation"
If, while filling an output line, it is discovered that the next
word will not fit, an attempt is made to hyphenate it.
Although 'fmt'
is usually quite good in its choice of where to split a word,
it occasionally makes a gaffe or two, giving reason to want to
turn the feature off. Automatic hyphenation can be disabled
with the 'no-hyphenation' command
.be
 [bf .nh]
.ee
long enough for a troublesome word to be processed, and then
reenabled with the 'hyphenate' command
.be
 [bf .hy]
.ee
Neither command causes a break.
.#
.SH "Margin Adjustment"
After filling  an output line, 'fmt' inserts  extra
blanks between words so that the last
word on the line is flush with the right margin, giving
the text a "professional" appearance.  This is
one of several margin adjustment modes that can be
selected with the 'adjust' command
.be
 [bf .ad] <mode>
.ee
The optional parameter <mode> may be any one of four single
characters: "b", "c", "l" or "r".
If the parameter is "b" or missing, normal behavior will prevail -- both
margins will be made even by inserting extra blanks between words.
This is the default margin adjustment mode.
If "c" is specified, lines will be shifted to the right so that they
are centered between the left and right margins.
If the parameter is "l", no adjustment will be performed;
the line will start
at the left margin and the right margin will be ragged.
If "r" is specified, lines will be moved to the right so that the
right margin is even, leaving the left margin ragged.
.pp
The 'no-adjustment' command
.be
 [bf .na]
.ee
has exactly the same effect as the following 'adjust' command:
.be
 [bf .ad] l
.ee
No adjustment will be performed, leaving the left margin even
and the right margin ragged. In no case does a change in the
adjustment mode cause a break.
.#
.SH "Centering"
Input lines may be centered, without filling, with the help of the
'center' command
.be
 [bf .ce] N
.ee
The optional parameter N is the number of subsequent input
lines to be centered between the left and right margins.
If the parameter is omitted, only the next line of input text
is centered. Typically, one would specify a large number, say
1000, to avoid having to count lines; then, immediately
following the lines to be centered, give a 'center' command
with an parameter of zero.  For example:
.be 5
 [bf .ce] 1000
 more lines
 than I care
 to count
 [bf .ce] 0
.ee
It is worth noting the difference between
.be
 [bf .ce]
.ee
and
.be
 [bf .ad] c
.ee
When the former is used, an implicit break occurs before each
line is printed, preventing filling of the centered lines;
when the latter is used, each line is filled with as many words
as possible before centering takes place.
.#
.SH "Sentence Punctuation"
By default, 'fmt' adds an extra blank after punctuation at the
end of a sentence; specifically, after periods, colons,
exclamation points and question marks.
This may not be desirable, particularly when abbreviations or
a person's initials are involved.
Thus, it can be turned on and off at will.
The 'single-blank' command
.be
 [bf .sb]
.ee
turns the mode off, while the 'extra-blank' command
.be
 [bf .xb]
.ee
turns it back on again.  As with hyphenation, neither command
causes a break.
.#
.BT 35 "Summary - Filling and Margin Adjustment"
?RQ  ".ad <mode>"  """b""" """b"""  no
Set margin adjustment mode.
?RQ  .br  -  -  yes
Force a break.
?RQ  ".ce N"  N=0  N=1  yes
Center N input text lines.
?RQ  .fi  on  -  no
Turn on fill mode.
?RQ  .hy  on  -  no
Turn on automatic hyphenation.
?RQ  .na  -  -  no
Turn off margin adjustment.
?RQ  .nf  -  -  yes
Turn off fill mode. (Also inhibits adjustment.)
?RQ  .nh  -  -  no
Turn off automatic hyphenation.
?RQ  .sb  "off"  -  no
Single blank after end of sentence.
?RQ  .xb  on  -  no
Extra blank after end of sentence.
?ET
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